First mutation in the red blood cell-specific promoter of hexokinase combined with a novel missense mutation causes hexokinase deficiency and mild chronic hemolysis.
Haematologica
; 94(9): 1203-10, 2009 Sep.
Article
en En
| MEDLINE
| ID: mdl-19608687
ABSTRACT
BACKGROUND:
Hexokinase is one of the key enzymes of glycolysis and catalyzes the phosphorylation of glucose to glucose-6-phosphate. Red blood cell-specific hexokinase is transcribed from HK1 by use of an erythroid-specific promoter. The aim of this study was to investigate the molecular basis for hexokinase deficiency in a patient with chronic hemolysis. DESIGN ANDMETHODS:
Functional studies were performed using transient transfection of HK promoter constructs in human K562 erythroleukemia cells. The DNA-protein interaction at the promoter of hexokinase was studied using electrophoretic mobility shift assays with nuclear extracts from K562 cells. DNA analysis and reverse transcriptase polymerase chain reaction were performed according to standardized procedures.RESULTS:
On the paternal allele we identified two novel mutations in cis in the erythroid-specific promoter of HKI -373A>C and -193A>G. Transfection of promoter reporter constructs showed that the -193A>G mutation reduced promoter activity to 8%. Hence, -193A>G is the first mutation reported to affect red blood cell-specific hexokinase specific transcription. By electrophoretic mobility shift assays we showed that in vitro binding of c-jun to an AP-1 binding site was disrupted by this mutation. Subsequent chromatin-immunoprecipitation assays demonstrated that c-jun binds this region of the promoter in vivo. On the maternal allele we identified a novel missense mutation in exon 3 c.278G>A, encoding an arginine to glutamine substitution at residue 93, affecting both hexokinase-1 and red cell specific-hexokinase. In addition, this missense mutation was shown to compromise normal pre-mRNA processing.CONCLUSIONS:
We postulate that reduced erythroid transcription of HK1 together with aberrant splicing of both hexokinase-1 and red cell specific-hexokinase results in hexokinase deficiency and mild chronic hemolysis.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Mutación Missense
/
Eritrocitos
/
Hemólisis
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Enfermedades Genéticas Congénitas
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Hexoquinasa
Tipo de estudio:
Etiology_studies
/
Prognostic_studies
Límite:
Adult
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Humans
/
Male
Idioma:
En
Revista:
Haematologica
Año:
2009
Tipo del documento:
Article
País de afiliación:
Países Bajos